Web and bituminized article made therefrom and process of making same



Patented Aug. 18, 1936 UNITED STATES PATENT OFFICE WEB AND BITUMINIZEDMADE THEREFROM AND PROCESS OF MAKING SAME por'ation of Ohio No Drawing.Application May 25, 1933,

7 Serial No. 672.907

15 Claims.

This invention relates to webs and bituminized articles made therefromand to the process of making the same. It also relates to fibrous websor felts which are impregnated with bituminous saturants or otherimpregnating materials and which are designed to afford roofing,flooring and other building materials and the like.

It is an object of'this invention to afiord web material which, has highflexibility and tear-resistance and at the same time possesses hightensile strength and toughness.

It is a further object of this invention to afford a bituminized web tobe used for roofing, flooring and the like which has the combinedproperties of high tear-resistance, high flexibility, toughness, hightensile strength and good weathering and wearing properties.

There are on the market at the present time certain types of wood fiberwhich will be referred to herein as purified fiber. erties the purifiedfiber is notable for its flexibility, softness, high absorbency andresistance to weathering or deterioration under atmospheric influences.is distinguished by a relatively high a cellulose content, a relativelylow content of p and 'y celluloses, a low lignin content and a pentosancontent approximating that found in unbleached coniferous sulphitepulps. One type of purified fiber which may be used for purposes ofillustration herein has an a cellulose content of about 93% or more,about 0.1% to 4% each of the p and 'y celluloses, a lignin contentusually less than about 1%, a pentosan content of about 1% to 4% and aresin content of usually less than about 0.5%.

We have found that when purified fiber is mixed with suitable unpurifledfiber, and a web is then made up from the mixed fiber as describedherein, the resultant web has properties which are different from andare distinctly superior to, for many purposes, the properties of webswhich are composed substantially of purified fiber on the one hand orunpurified fiber on the other.

Unpurified fiber" as that term is used herein refers to the ordinarytypes of kraft and sulphite pulps, kraft paper scrap, felt-makers rags,cotton mill waste, cotton linters, wool carpet clippings and the like. a

Improvements in webs, bituminized or otherwise can be best recognized bythe degree to which In physicalprop- In chemical properties purifiedfiber they respond to certain tests for determining such characteristicsas tear-resistance, bursting strength, resistance to failure underflexing, tensile strength, elongation, toughness and resistance toindentation. Such tests are well known in the art and completedescriptions of apparatus used and methods of making tests on felts, andbituminized roofings and floorings will be found in Asphalts and AlliedSubstances by Abraham, 1929 edition, and in Paper Testing Methodspublished by the Technical Association of the Pulp and Paper Industry,1929- edition. Brief reference to certain tests will, however, be madeherein as follows:

, Tear-resistance as given herein is determined by using the standardElmendorf tear tester, the results being given in grams, for a singlethickness of the sheet. The test is to be assumed to be taken at 77 F.unless otherwise stated.

Bursting strength is detemiine'd by the stan ard Mullen tester, in whicha sheet of the ma terial is subjected at about 77 F. to tensionuniformly increased on a one square inch area by pressure applied to arubber diaphragm under a uniform rate of displacement of anincompressible fluid, until the sample ruptures.

Resistance to failure under flexing may be determined in several ways,as hand flexing or bending around mandrels of various diameters,particularly at low temperatures. The Reeve and Yeager flexibilitytester is a suitable instrument for such tests.

Tensile strength is determined by the use of standard Amsler or Scotttensile testing machines. Samples 2 inches wide by 5 inches long clampedbetween the jaws are stressed in tension. The maximum load sustained bythe material expressed in pounds per inch of width of the sample or persquare inch of original cross-section is taken as the tensile strength.

In testing the material on the Amsleror Scott testing machine as abovedescribed the elongation up to maximum tensile load, in per cent, is

' the "elongation value. 'The material in most cases continues toelongate after maximum tensile load is reached, until the breaking pointis reached. Elongation up to the breaking point in per cent is taken asthe total elongation."

The work done in bringing the material up to maximum load is taken asthe toughness value.

Itmay be calculated from the area between the stress-strain curve andelongation axis up to the maximum load point and is expressed as work'absorbed per cubic inch of material.

Resistance to indentation is determined by placing a sample of thebituminized web on a piece of sponge rubber sheet V inch thick and thensubjecting the sample for one hour to a inch diameter steel ball-bearingsupporting a vertically imposed load of -5 kilograms. The

' depth of indentation of the ball into the sample of the saturated andunsaturated sample divided by the weight of the unsaturated sample,multiplied by 100 is the percent kerosene absorption.

The purpose of the kerosene absorption test is to determine 'theabsorbency or porosity of the web, with particular reference to itssaturating capacity" for asphalt or other thermoplastic impregnatingmaterials.

This invention will now be illustrated in connec tion with certainspecific examples of the combination in webs of purified and unpurifiedfibers according to this invention.

This invention will first be exemplified in connection with a water-laidfelted web containing about 60% of purified fiber and about 40% of kraftfiber. In the manufacture of the web the purified fiber is preferablybeaten separately until the lumps are substantially removed and thefibers are thoroughly distributed. Excessive beating beyond what isnecessary to distribute the fiber and remove lumps is preferablyavoided.

Since in preferred practice the beating is only enough to distribute thefiber and remove lumps, such fiber may be referred to herein assubstantially unreduced to distinguish such fiber from fiber which hasbeen subjected to more prolonged beating that results in substantialreduction in size of the fiber. The kraft fiber is preferably beatenuntil the fiber has been reduced to a furnish which would besatisfactory in making kraft paper. The purified fiber and kraft fiberare then blended in desired proportions. The mixed fiber furnish, atsuitable dilution, is then taken to a paper-making vat wherein aninterfelted web is formed on a paper-making screen cylinder as is wellknown in the art. A Fourdrinier papermachine may also be used forformation of the web. The web is then subjected toroliing and dryingmechanisms which need not be described as numerous types of suchmechanisms are well known in the art. 1

By adjusting the dilution of the fiber in the cylinder vat, the cylinderwater level differential and/or the pressure on the couch roll and pressrolls the density of the felt or index of'eompactness can be controlled.The index of compactness is computed by the following formula:

caliper of the sheet in mils number index of compactness wherein thefelt number is the weight in pounds of 480 square feet of felt. Thegreater the numerical value of the compactness index the less compactand more absorbent is the felt.

In one example a felted web is made up having an index of compactness ofabout 1.0 (i, e, haying i... pk.

a felt number of 68.0 and a caliper of .071 inch). The sheet isformedunder a pressure of about pounds per square inch. The dry felt (60%purified fiber and 40% kraft fiber) is found to, have the followingcharacteristics as compared with a felt made 100% from purified woodfiber under similar conditions duringinitial formation of the wet web,but subjected thereafter to a pressure 0 only about 10 lbs. per squareinch.

The web made up and formed as above described is thus seen to have veryhigh tear-resistance and Mullen strength. When compared with felt madeup using 100% purified fiber under similar conditions, the new web isfound to have over six times the tear-resistance and over four times theMullen strength of web composed of 100% purified fiber. Moreover, thenew web shows containing higher lignin and/or pentosans and which ishard and stiff, as described herein, appears to impart to the felted webthe unusual combination of characteristics above described.

- Thus in the above illustration the kraft fiber mentioned has a lignincontent of about 4% to about 8% and a pentosan content of about 6% toabout 0%. In the case of wood fiber, fiber having more than about 6%pentosan and/or about 4% lignin is preferable as hard type fiberfor'addition to purified fiber.

While relatively high lignin andyor pentosans are believed to impartstiffness and hardness to unpurified wood fibers, particularly thoseliberated by alkaline treatment, fiber of hard type may be used which isstiff and-hard by virtue of other characteristics and illustrations ofsuch additional hard type fibers will be given below. Thus, whilespecific mention of kraft fiber is made in the above example, other hardtype fiber may also be used instead of kraft fiber as will be disclosedmore in detail below.

While a specific proportion of-purified and kraft fiber and a specificindex of compactness are mentioned above, it is to be'understood thatthis has been done for purposes of illustration only. Thus by reducingthe. water level differ- 1 ential in the cylinder vat or by lowering thepressure on the couch rolls the index of compactness can be increased.Thus a pressure of 10 pounds per square inch gives a web wh'ich is lesscompact and more porous. Variation in proportions of purified cellulosewood fiber and unany grade of purified or unpurified fiber suitable formaking felts and papers may be employed.

Web material, particularly water-laid felts, containing mixtures ofsubstantial proportions of purified fiber and of unpurified fiber and inan unimpregnated condition, are to be regarded as a feature of thisinvention. Moreover, such webs, when impregnated with a saturatingcompound or compounds such as bituminous cements, hydraulic ,cements,rubber latex, resins, varnishes or other binders such as sodium silicateand the like, also exhibit remarkably improved properties and are to beregarded as being within the scope of this invention. The employment ofthe purified fiber in major proportions and the blending of the purifiedfiber with hard type fiber such as kraft are further features of thisinvention.

When web material embodying this invention is bituminized, as in themanufacture of roofing or flooring materials, the bituminized web hasnew and improved properties, but not in the direct ratiofound in theunsaturated webs and such bituminized webs are to be regarded as aparticular feature of this invention. This will be brought out inconnection with specific examples of bituminized webs embodying thisinvention to be given below.

The felt after having been formed is then im-,

pregnated with bituminous saturant. In the concrete example'here givena. web having'an index of compactness of about 1.30 isimpregnated with asaturant having a softening point of about F. (by the ball and ringmethod) and a penetration of about at 77 F. The saturant is preferablyapplied" at a temperature of about The impregnation operation may becarried out by any suitable apparatus of which several types are known.The felt will be found to absorb the bituminous saturant much morereadily than does ordinary roofing felt and to take up about 225% to275% of asphalt on the weight of the dry felt. These figures have beenfound to be preferable in the manufacture of roofing described herein.While the fibrous web could be made so soft and porous as to absorbstill further quantities of saturant, it has been found that furtherquantities of saturant result in decreased mechanical properties such astear-resistance and Mullen strength, elongation under tensile loads. Arelatively high proportion of saturant such as within the range of theproportions mentioned, is, however, desirable in affording roofinghaving very high resistance to weathering. In the illustration giventhere is absorbed in the web about 240% of saturant. i

The saturated felt is then treated with a bituminous coating on bothsides, having, for example, a softening point of about 235% F. and apenetration of about 13 at 77 F. The coating material is maintained atabout 375 F. for the coating operation. Flake mica is applied as asurface mineral layer on the finished roofing.

accompanied by excessive,

. The roofing material made as above described,

to a finished weight of about 75 lbs. per 108 sq. ft., is found to havethe following characteristics as determined by tests above described, incomparison with rag felt roofing of high quality.

The tear-resistance of the bituminized web is relatively high not onlyat 77 F. but at lower temperatures as well. Thus breaking and crackingof roofing materials when handled at low temperatures is reduced.

The foregoing data show that the roofing thus produced has a very hightear-resistance and a high bursting strength (Mullen). The strength,elongation and toughness values are very much greater than those ofbituminized felt roofings heretofore manufactured. Properties such asthese afford roofing which is highly resistant to tearing duringapplication and to pulling and tearing at na ls. The elongation of thematerial makes it well suited for roofing purposes. In the first placethe material does not elongate excessively and therefore does not tendto stretch out of shape and become permanently deformed. On the otherhand, it is not excessively short, and the roofing has sufiicientelongation so that it is capable of adapting itself without rupture todeformations and movements of roof decks to which it is secured.

The foregoing is illustrative of a felt desirable for roofing. Forpurposes of further illustration a bituminized web especially adaptedfor flooring will be given.

The web for the flooring may be made up for thepurpose 'of thisillustration by using about 80% purified fiber and about 20% kraftfiber. The method of manufacturing the flooring felt is the same as thatemployed in making the roofing except that the dilution of the mixedfiber furnish, the cylinder vat water level differential and thepressure on the couch and press rolls are adjusted so that the index ofcompactness will be about 0.95 to about 1.15, values which have beenfound to be desirable in the manufacture of flooring. In theillustration given the web has an index of compactness of about 1.05,(i. e., a caliper of .060" and a felt number of 57).

The saturant used in the flooring has a softening point of about 160 F.and a penetration of about 25 at 77 F. and is applied at a temperatureof about 400 F. The felt preferably is caused to take up on thesaturating machine about 125% to 150% of saturant and in theillustration here given there is 137% of absorbed saturant. Excess ofsaturant may cause bleeding and staining of the surface of the flooring.The saturated felt is given a'coating of priming paint, followed by acoating of print paint and a surface finish of lacquer and is then bakedfor four or five days at 140-150 F., the finished flooring having acaliper of about .071" and weighing about 40 lbs. per 100 sq. ft.

The resulting product when tested is found have the followingcharacteristics, in comparison with a high quality r the same way.

' Purified Rag felt fiberfiooring kraft ielt flooring Tear-resistanceper .001" thickness of base felt, grams 24. 2 48. l Bursting strength(Mullen) lbs 166 295 Tensile strength, lbs. per inch width,

. average-- 102 133 Elongation, rcent 4.0 5.8 Tensile l at 2%elongation, lbs.,

average"-.. 86 liB Indentation, nun l. 8 l. 0

From the above data it is seen that the flooring is very resistant totearingand that the Mullen strength and tensile strength are high.More-.

over, the material is flexible and capable of being rolled and unrolledwithout cracking, but is not subject to excessive stretching anddeformation. The flooring is resistant to indentation.

'. about 40% of kraft fiber is used with about to about 80% of purified.fiber, with minor proportions of unpurified fiber other than kraft. Inthese proportions a high degree of tear-resistance is retained. Inunimpregnated webs a higher proportion of kraft fiber can be employedwithout sacrifice of tear-resistance.

While the employment of kraft fiber is regarded as preferable accordingto this invention other fiber may be used such as cotton and wool No. land No. 2 felt-makers (roofing) rags, cotton linters, cotton mill waste,wool, wool waste, wool carpet clippings, jute and the like. Thecharacter of these fibers is such that they make up harder, denser andless absorbent felt or other web than does the purified fiber. Fibersuch as illustrated will be referred to as hard type" fiber herein. Socalled "mixed paper fiber is also to be regarded as hard type fiber.

Mixtures of purified fiber and hard type fiber, with other fibersmayalso be employed in the practice of this invention. In the practice ofthis invention itis preferable to employ with the purified fiber amixture of hard type fiber and other fiber which produces a harder,denserand stronger felt or other'web than does the purified fiber byitself.

Thus, for example, felts may be manufactured containing about purifiedfiber, about 30% kraft and about 10% cotton waste, or containing about50% purified fiber, about 40% kraft and about, 10% wool carpetclippings. Such felts when impregnated with roofing or flooringsaturants produce superior roofings and fioorings.

In the practice of this invention it-is preferable to employ a majorproportion of purified fiber and about 10% to 50% of hard type fiber.Particularly satisfactory results are obtained "when felt fiooring madein of unpurified fiber are used, e. g., up to as much as 50% inproportion to the purified fiber, it is preferable to employ lesserdegrees of pressure in making the'web as by increasing the proportionsof unpurified fiberthe susceptibility of the web to impregnation isdecreased.

The-following is a table giving the approximate softening points (by theball and ring.

method) and penetration of bituminous saturants, desirable for roofing,and flooring.

Softening Pentera- Bitumen point tion at Shingle saturant -200 45-70Roll roofin saturant 76-100 45-200 Flooring ie t saturant. -1 15-80Shingle coating -275 5-50 Roll roofing coating--. 190-275 10-50 Theabove table is, designed merely to define generally the types ofasphalts which are useful in the manufacture of bituminized webs for thepurposes stated and is intended as a guide in the selection by oneskilled in the art of bituminous saturants and coating materials whichmay be used in the practice of this'invention. The'type of saturant usedwill depend upon the properties ,desired in the finished product andupon the compactness and strength qualities of the'felt web which is tobe impregnated.

While this invention has been described in connection with certainspecific examples it is to be understood that this has been done merelyfor the purpose of illustration and that the scope of this invention isnot to be limited thereby.

Moreover, while certain data has been given as to the results of testsupon certain examples of materials embodying this invention, it is to beunderstood that this has been done merely for the purpose of affording'a better understanding of this invention without imposing a limitationthereon and that in different embodiments of vary depending upon thetypes and proportions of material used, the process of manufacture andthe like within the scope of this invention as determined by thelanguage of the following claims.

We claim: 1. As an article of manufacture a felted web having an indexof compactness of approximately this invention the specific propertie'sthereof will 0.95 to approximately 1.4 and containing a major proportionof substantially unreduced purified cellulose wood fiber interfeltedwith over about 10% of a harder type wood fiber than said purifiedfiber, said web being impregnated with a bituminous saturant.

2. As an article of manufacture a felted web.

containing purified cellulose wood fiber as a major portion interfeltedwith a minor portion of harder type substantially unpurlfied fiberincluding kraft fiber and a fiber selected from a group consisting ofcotton linters, jute, wool, cotton mill waste,

typewoodfiberthansaidpurifiedfiberasaminorportion of fiber, said webbeing impregnated with a bituminous saturant. to the extent of about225% to about 275% on theweight of dry web and odd amt having I,softening point 0! from about to about 200 F. and a penetration of about200 to about 5 at 77 F.

4. As an article of manufacture a felted web having an index ofcompactness of from about 0.95 to about 1.15 and containing puriedcellulose fiber as a major portion of fiber and as a minor portion ofwood fiber a harder type fiber than said purified fiber, said web beingimpregnated with bituminous saturant to the extent of about 125% toabout 150% on the weight of dry web and said saturant having a softeningpoint of about 115 F. to about 200 F. and-a penetration of about toabout 15.

5. As roofing material, a felted web having an index of compactness offrom about 1.20 to about 1.40 and containing from about 50% to about 80%of substantially unreduced purified cellulose wood fiber and about 10%to about 40% of substantially unpurified kraft fiber, said web beingimpregnated to the extent of about 225% to about 275% on the weight ofdry web with bituminous saturant having a softening point of from about75 F. to about 200 F., said bituminized web having a surface coating ofbituminous material.

6. As a flooring material a felted web having an index of compactness offrom about 0.95 to about 1.15 and containing about 50% to about 80% ofsubstantially unreduced purified cellulose wood fiber and about 10% to40% of substantially unpurified kraft fiber, said web being impregnatedto the extent of about 125% to about 150% on the weight of dry web witha bituminous saturant having a softening point of about to about 200-F., said bituminized web having a wear-resistant surface coating.

7. A process of making a water-laid felted web containing a mixture ofpurified cellulose fiber and unpurified fiber which comprises beatingthe purified fiber separately only until lumps are substantially removedand without substantially reducing said fiber in size, beating theunpurified fiber separately until lumps are substantially removed anduntil the unpurified fiber has been reduced to a paper making furnish,mixing the separately beaten fibers and blending same and thereafterforming the same into a felted web in a paper making operation includingfelting the aqueous fiber furnish on a screen and pressing the resultingfelt, the dilution of the furnish and the pressure of the pressingresulting in a web having an. index of compactness of approximately 0.95to approximately 1.4.

8. As an article of manufacture, a felted web having an index ofcompactness of between approximately 0.95 and approximately 1.4 andcomprising over about 50% of substantially unreduced purified cellulosefiber. interfelted with about 10% to 50% of substantially unpurifiedkraft fiber.

9. As an article of manufacture, a felted web having an indexofcompactness of between approximately 0.95 and approximately 1.4 andcom-v with a minor proportion of alkali-liberated wood fiber adapted forpaper making and containing over about 6% of pentosans and over about 4%of lignin.

10. As an article of manufacture a felted web having an index ofcompactness of between approximately 0.95 and approximately 1.4 andcomprising a major proportion of substantially unreduced purified woodfiber and over about 10% of substantially reduced wood fiber of hardertype than said purified fiber.

11. As an article of manufacture a felted web having an index ofcompactness of between approximately 0.95 and approximately 1.4 andcomprising a substantial proportion of substantially unreduced purifiedcellulose fiber interfelted with a substantial proportion of wood fiberwhich is harder. and less absorbent than said purified fiber.

12. As an article of manufacture a felted web containing over about 50%of substantially unreduced purified cellulose fiber and over about 10%of substantially reduced unpurified wood fiber.

13. As an article of manufacture, a felted web having an index ofcompactness of from about 0.95 to about 1.4 and containing purifiedcellulose fiber as a major portion of fiber and as a minor portion offiber over 10% of a substantially harder type wood fiber than saidpurified fiber, said web being impregnated throughout with bituminoussaturant.

14. As an article of manufacture, a felted web having 'an index ofcompactness of from about 0.95 to about 1.4 and containing purifiedcellulose fiber as a major portion of fiber and as a minor portion offiber over 10% of a substantially harder type wood fiber than saidpurified fiber, said web being impregnated throughout with bituminoussaturant, to the extent of about to about 275% on the weight of my weband said saturant having a softening point of from about 75 F. to about200 F.

15. As an article of manufacture, a felted web having an index ofcompactness of from about 0.95 to about 1.4 and containing purifiedcellulose fiber as a major portion of fiber and over about 10% of kraftfiber, said web being impregnated HAROLD w. GREIDER. GEORGE ARTHURFASOLD.

CERTIFICATE OF CORRECTION.

Patent No. 2,051,168. August 18, 1936.

HAROLD W. GREIDEB, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 3,first column,.. line 71 for "235%" read 235; and second column, line 14,in the table, column 1, for "xtrength" read strength; page 5, firstcolumn, line 5, claim 4, for "puried" read purified; and that the saidLetters Patent should be read with these corrections therein that thesame may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of March, A. D. 1937.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

